Of the 55 classmates who graduated from his Plaquemines Parish high school in 2005 with Richie Blink only about a half dozen stuck around. Blink tried moving to Baton Rouge, where he worked at the airport and got his pilot’s license, but the land drew him back. What’s left of the land, that is.

Blink won’t quit on the Mississippi River Delta, which is disappearing at the rate of a football field an hour in what some have called the Western Hemisphere’s biggest environmental disaster after the deforestation of the Amazon.

One goal is to rebuild a 50-mile buffer against ocean storm surges that has been erased in a single human lifetime, a buffer that might have eased the hurt to New Orleans from Hurricane Katrina.

Mostly open bay just over the levee that shields the Mississippi from the Gulf of Mexico

Blink sets off from the wharf at Buras _ where Katrina made landfall _ in a fisherman’s skiff into a mostly open bay with sparse clumps of marsh grass.

We’re 70 miles southeast of New Orleans on the right bank of the Mississippi. This is the sliver of land, sheltered on both sides by 20-foot-high levees, that those who remain inhabit. Rebuilt homes on the peninsula _ including the high school _ are raised on piles driven deep into sandy soil.

Blink shows us where engineers have built an “oyster break” in the shallow water by the wharf. It’s a concrete honeycomb designed to help rejuvenate the oyster population .

He opens up the throttle and the boat slides through heavily brackish water.

“When I was a kid, this was all little bayous, meandering streams. I spent a lot of time here,” he says.

Shrimp boat in mostly barren salt marsh

We pass a working shrimp boat and an old abandoned fishing camp on stilts.

A little more than a decade ago, the place was crawling with alligators and other wildlife, a teeming coastal swamp. Now, the Gulf of Mexico is in charge.

Man-made berm on the Gulf of Mexico side

We pull up to a barrier being built by barges that dredge the bottom and hurl muck over the berm. This is land-building. And it’s expensive.

The government has spent $300 million building a barrier a few miles away across more than 30 miles of coastal islands fronting the gulf.

It’s six feet high in some places.

But it’s not holding back the tide. Sea levels are on the rise with global warming. But that’s the least of it.

The reason the Mississippi Delta has been sinking by much as a meter a century is human engineering. It’s part of the reason half of New Orleans is now below sea level.

By stringing levees up and down the length of the Mississippi to protect homes and businesses from flooding, we have robbed the great river of vigor, diminishing the flow of silt that, since the last ice age ended 7,000 years ago, made the delta. Once meandering, the river is now straight-jacketed. Successful river control has degraded coastal wetlands.

The greatest flood danger now comes not from the Mississippi but the ocean, as Katrina proved.

Worsening matters, the energy industry has since the 1930s dug some 20,000 miles of canals in the delta to extract oil and natural gas and service pumping operations.

Add to that as aggravating factor the introduction of an invasive South American rodent, the nutria. It devours root systems _ yet another coastal erosion engine at work.

The toe of the boot that is Louisiana is wasting away. The physical version we know from maps is no longer true. The boot is not solid. It is gossamer.

“This is the dying side of the river,” says Blink. We head back to the marina. Blink runs the skiff up on its trailer.

It’s time to head over to the Mississippi and drop in there. We’ve done the bad news piece of our vanishing coastline tour.

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Buras, Louisiana

Blink works as Coastal Zone Program Manager for Plaquemines Parish. He ensures coastal restoration projects are built as designed. The job dovetails with his passion of fighting to preserve a peninsula that four in five residents abandoned after Katrina.

They run educational tours of these wetlands in kayaks. And Blink plants cypress trees, well over 10,000 to date, to fight the ravages of sinking soils and salt water seepage.

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We cross the Mississippi to its left bank, what Blink calls the bank of hope.

Mississippi River lock, left bank, Buras, Louisiana

A few locks separate the river here from marshlands and estuaries to the northeast.

But there are also breaches, crevasses they’re called. We drop down one, the boat swirling in a churning whirlpool.

Below a crevasse, fresh water spills into a healthy tidal marsh

Soon, we are motoring through true tidal marsh. We hear songbirds, see fish jump. Marsh grass, cattails and lotus pods abound. A farmer still grazes cattle on land above one bayou.

Blink navigates into a narrow channel where grass gets caught in the outboard’s propeller.

He is taking us to a cemetery whose graves _ several score _ date back to the 1830s. The most recent is from 1976 and relatives still tend it, cutting the grass and even bringing flowers from time to time.

Blink does his best not to get too heartsick. But he has no illusions.

Stacked up against the coastal reconstruction campaign he champions are an influential lot: oyster and shrimp fishermen, the oil and gas industry.

He realizes that he and others who are bound sentimentally to the disappearing delta and are trying to turn back the rising tide will most likely have to settle, if they want to stick around, for what climate scientists call adaptation.

“Either your house will be on stilts,” he says, “or on an earthen mound.”